Hi, I have built a 32-bit GCC 8.3.0 (no multi-lib support) on RHEL 5 and a 64-bit GCC 8.3.0 (again, no multi-lib support) on CentOS 5.11. What I find interesting is that when I go to compile a program that will need atomic locks (a Boost template class pulled in via a header file), the 32-bit object code requires the library -latomic, but 64-bit object code does not require that. Looking over "info gcc" I see a multitude of options for atomic operations. The take away for me sis that for architectures that have an instruction set that has support for atomic operations, libatomic is not necessary, but for other architectures, it is. Is this a correct analysis. If you need more specific data from me, let me know. Thanks and regards, Tom